Here is the summary i found online. Please don’t summarize this paragraph too short and keep all the details please.
Once again, Gandalf disappoints the company by announcing that he must leave. He says, however, that he will stay around long enough to help them find food and ponies so that they can make their way on their own through Mirkwood—the last great obstacle before the Lonely Mountain. He leads them to the house of Beorn. Beorn is a half-man, half-bear creature who has a great wooden house in the middle of the woods outside Mirkwood. Gandalf takes the dwarves to Beorn’s house a few at a time, so as not to startle him. He tells Beorn the story of their adventure in the mountain. Gandalf’s story amuses Beorn greatly because he despises goblins, who are enemies of nature.
Beorn offers the company much-needed food and lodging. He also does some scouting and finds that the Wargs and goblins have put together an attack party in order to find the dwarves and wizard that killed their leader, the Great Goblin. To evade this attack party, Beorn recommends that the group take the northern pass (the elf path) through Mirkwood, which will bring them near the Lonely Mountain. This choice will throw the goblins off the company’s trail and allow them to bypass the dangerous southern pass. The northern pass is not entirely safe either, so Beorn repeatedly warns his guests never to stray from the path.
Beorn provides the group with food and ponies to carry them to the gate at the path’s start. From there, however, they must return the ponies and travel on foot. When they reach the path, Gandalf also departs, wishing his friends the best and reminding them never to stray from the path—dark things lurk in Mirkwood that even the wizard does not know about. On that note, the dwarves and the hobbit plunge into the forest.